Transmitter Apparatus, Receiver Apparatus, and Radio Communication System

1. A receiver apparatus for receiving, by a plurality of receiver antennas, transmission signals transmitted from a transmitter apparatus by a plurality of transmitter antennas in a parallel manner and for estimating a channel matrix for causing the transmission signals to be related to received signals to demodulate the received signals based upon said channel matrix; the receiver apparatus comprising: calculation means for calculating a physical amount so as to estimate a radio line quality with respect to each of signal series based upon only said channel matrix; determination means for evaluating the radio line quality based upon the physical amount calculated by said calculation means so as to determine a transmission parameter in a next transmission operation by said transmitter apparatus with respect to each of the signal series; transmission means for transmitting the transmission parameter determined by said determination means to said transmitter apparatus; and detection means for detecting a change in the transmission parameter from the received signals with respect to each of the signal series, wherein the transmission parameter is a modulation level in mapping.

2. A receiver apparatus as claimed in claim 1 wherein, said physical amount is a signal-to-noise ratio (SNR) of said demodulated signals.

3. A receiver apparatus as claimed in claim 1 wherein, said physical amount corresponds to a sum of signal-to-noise ratios (SNRs) of signals which are detected by said plurality of receiver antennas when it is assumed that said plurality of transmitter antennas separately transmit signals.

4. A receiver apparatus as claimed in claim 3 wherein, said physical amount corresponds to a sum of one, or a plurality of said SNRs having larger values.

5. A receiver apparatus as claimed in claim 1 , wherein said estimates the channel matrix using a pilot signal output by said transmitter apparatus, and wherein no information obtained by demodulating the received signals is utilized by said calculation means in calculating the physical amount.

6. A radio communication system comprising a transmitter apparatus for transmitting transmission signals by a plurality of transmitter antennas in a parallel manner; and a receiver apparatus for receiving said transmission signals by a plurality of receiver antennas, a for estimating a channel matrix for causing the transmission signals to be related to received signals to demodulate the received signals based upon said channel matrix; wherein said receiver apparatus comprises: calculation means for calculating a physical amount so as to estimate a radio line quality with respect to each of signal series based upon only said channel matrix; determination means for evaluating the radio line quality based upon the physical amount calculated by said calculation means so as to determine a transmission parameter in a next transmission operation by said transmitter apparatus with respect to each of the signal series; transmission means for transmitting the transmission parameter determined by said determination means to said transmitter apparatus; and detection means for detecting a change in the transmission parameter from the received signals with respect to each of the signal series; and wherein, said transmitter apparatus comprises: reception means for receiving said transmission parameter transmitted by said determining means; and means for controlling the transmission operation with respect to each of the signal series based upon said transmission parameter received by said reception means, wherein the transmission parameter is a modulation level in mapping.

7. A radio communication system as claimed in claim 6 wherein, said physical amount is a signal-to-noise ratio (SNR) of said demodulated signals.

8. A radio communication system as claimed in claim 6 wherein, said physical amount corresponds to a sum of signal-to-noise ratios (SNRs) of signals which are detected by said plurality of receiver antennas when it is assumed that said plurality of transmitter antennas separately transmit signals.

9. A radio communication system as claimed in claim 8 wherein, said physical amount corresponds to a sum of one, or a plurality of said SNRs having larger values.

10. A radio communication system as claimed in claim 6 , wherein said estimates the channel matrix using a pilot signal output by said transmitter apparatus, and wherein no information obtained by demodulating the received signals is utilized by said calculation means in calculating the physical amount.

11. A transmitter apparatus for transmitting data by a plurality of transmitter antennas in a parallel manner to a receiver apparatus for receiving by a plurality of receiver antennas, said transmitter apparatus being used in a radio communication system in which a channel matrix for causing the signal transmitted by said transmitter apparatus to be related to said signal detected by said receiver apparatus becomes identical to a channel matrix for causing the signal transmitted by said receiver apparatus to be related to said signal detected by said transmitter apparatus; wherein, said transmitter apparatus comprises: estimation means for estimating said channel matrix; calculation means for calculating a physical amount so as to estimate a radio line quality with respect to each of signal series based upon only said channel matrix; determination means for evaluating the radio line quality based upon the physical amount calculated by said calculation means so as to determine a transmission parameter in a next transmission operation with respect to each of the signal series based upon the transmission parameter determined by said determination means, wherein the transmission parameter is a modulation level in mapping.

12. A transmitter apparatus as claimed in claim 11 wherein, said physical amount corresponds to a signal-to-noise ratio (SNR) of demodulated signals of said receiver apparatus.

13. A transmitter apparatus as claimed in claim 11 wherein, said physical amount corresponds to a sum of signal-to-noise ratios (SNRs) of signals which are detected by said plurality of receiver antennas when it is assumed that said plurality of transmitter antennas separately transmit signals.

14. A transmitter apparatus as claimed in claim 13 wherein, said physical amount corresponds to a sum of one, or a plurality of said SNRs having larger values.

15. A transmitter apparatus as claimed in claim 11 , wherein said estimates the channel matrix using a pilot signal output by said transmitter apparatus, and wherein no information obtained by demodulating the received signals is utilized by said calculation means in calculating the physical amount.

16. A radio communication system comprising a transmitter apparatus for transmitting transmission signals by a plurality of transmitter antennas in a parallel manner; and a receiver apparatus for receiving said transmission signals by a plurality of receiver antennas, a channel matrix for causing the signal transmitted by said transmitter apparatus to be related to said signal detected by said receiver apparatus becomes identical to a channel matrix for causing the signal transmitted by said receiver apparatus to be related to said signal detected by said transmitter apparatus; wherein, said transmitter apparatus comprises: estimation means for estimating said channel matrix; calculation means for calculating a physical amount so as to estimate a radio line quality with respect to each of signal series based upon only said channel matrix; determination means for evaluating the radio line quality based upon the physical amount calculated by said calculation means so as to determine a transmission parameter in a next transmission operation with respect to each of signal series; and means for controlling the transmission operation with respect to each of the signal series based upon the transmission parameter determined by said determination means; and wherein, said receiver apparatus comprises: means for detecting a change in said transmission parameter from the signals received from said transmitter apparatus with respect to each of signal series, wherein the transmission parameter is a modulation level in mapping.

17. A radio communication system as claimed in claim 16 wherein, said physical amount corresponds to a signal-to-noise ratio (SNR) of demodulated signals of said receiver apparatus.

18. A radio communication system as claimed in claim 16 wherein, said physical amount corresponds to a sum of signal-to-noise ratios (SNRs) of signals which are detected by said plurality of receiver antennas when it is assumed that said plurality of transmitter antennas separately transmit signals.

19. A radio communication system as claimed in claim 18 wherein, said physical amount corresponds to a sum of one, or a plurality of said SNRs having larger values.

20. A radio communication system as claimed in claim 16 , wherein said estimates the channel matrix using a pilot signal output by said transmitter apparatus, and wherein no information obtained by demodulating the received signals is utilized by said calculation means in calculating the physical amount.